Abstract: Carbon fiber composite core wire has many advantages, such as low density, high strength, high elastic modulus and low line loss, which can greatly improve the transportation capacity of the line.However, due to the lack of bending resistance and other human factors, there are various defects in the interior, which eventually lead to the occurrence of the breakage accident, which seriously endangers the operation safety of the line.The application status of carbon fiber composite wire was analyzed, and several common nondestructive testing techniques for carbon fiber composite core wire were summarized.The principle and characteristics of various technologies were analyzed, and the advantages and disadvantages of the related technologies were briefly described.Finally, it is pointed out that the nondestructive testing technology of carbon fiber composite core wire need a lot of research work.